1. Field of the Invention
The present invention relates to a tool changer for machine tools. In particular, the tool changer is equipped with a tool transfer mechanism that transfers a next-process tool, which has been transferred to a specified tool takeout position by a tool magazine, between the tool takeout position and a tool changing position.
2. Discussion of the Related Art
In some tool changers, there is a distance between the tool changing position set near the tool spindle and the tool takeout position for the next-process tool, which is set to the tool magazine. In such a case, generally, the tool changer is equipped with a tool transfer mechanism for transferring the next-process tool from the tool takeout position to the tool changing position.
An example of such a tool transfer mechanism is a tool transfer mechanism having an air cylinder mechanism that moves back and forth over a range from the tool takeout position to the tool changing position. In this device, a piston rod of the air cylinder mechanism is equipped with a tool pot for holding the next-process tool. The tool pot is linearly transferred between the tool takeout position and the tool changing position by the piston rod.
However, this conventional tool transfer mechanism requires a large-scale air cylinder mechanism having a stroke equal to or larger than the transfer distance of the tool pot. This poses the problem of increased installation space.
The present invention has been accomplished in view of these and other problems. Therefore, an object of the invention is to provide a tool changer for machine tools that is capable of transferring the tool pot with a stroke smaller than the transfer distance of the tool pot.
In order to achieve the above and other objects, the present invention provides a tool changer for machine tools comprising: a tool magazine having a multiplicity of tools, the tool magazine transferring and indexing a next-process tool to a predetermined tool takeout position; a tool transfer mechanism for taking out and transferring the next-process tool positioned in the tool takeout position to a tool changing position; and a tool changing mechanism for changing a tool loaded on a tool post with the next-process tool positioned in the tool changing position. The tool transfer mechanism comprises a transfer arm pivotably disposed so as to have a front end portion of the transfer arm move between the tool takeout position and the tool changing position, a tool holding member coupled to the front end portion of the transfer arm, the tool holding member supporting the next-process tool; and a cylinder mechanism coupled to the transfer arm for driving the transfer arm.
In an embodiment, the present invention provides a tool changer for machine tools as described above, further comprising a tool transfer pot for holding one of the tools, the transfer pot having an engaging groove extending in a tangential direction, and the tool holding member having a guide pin that engages with the engaging groove to thereby position and support the tool transfer pot axially and circumferentially.
According to the tool changer of the present invention, the transfer arm is pivotably provided between the tool takeout position and the tool changing position. The tool holding member is provided at the front end portion of the transfer arm. The cylinder mechanism for pivotally driving the transfer arm is coupled to the transfer arm. Therefore, the tool holding member can be transferred from the tool takeout position to the tool changing position with a stroke smaller than the travel distance of the tool holding member. As a result, the cylinder mechanism can be downsized proportionally. Consequently, the installation space can be reduced.
In an embodiment, an engaging groove is formed in the tool transfer pot and the tool holding member is provided with the guide pin to engage with the engaging groove. Therefore, when holding the tool transfer pot by the tool holding member, the tool transfer pot can be positioned in the axial and circumferential directions with reliability. Moreover, the tool transfer pot can be transferred to the tool changing position with the proper orientation. Thus the positioning accuracy of the cutting tool can be ensured in loading the next-process tool onto the tool spindle.